Multilayer golf ball and composition

ABSTRACT

A golf ball comprising a core, a cover, and at least one intermediate layer disposed between the core and the cover, wherein the core has a compression of less than about 60 and the intermediate layer is formed from a blend comprising a polyurethane material, wherein the golf ball has a compression of about 75 to about 85.

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/996,718, filed Dec. 23, 1997, now U.S. Pat. No. 6,124,389,which is a continuation-in-part of U.S. patent application Ser. No.08/606,373, filed Feb. 23, 1996, now U.S. Pat. No. 5,721,304, and also acontinuation-in-part of U.S. patent application No. 08/746,362, filedNov. 8, 1996, now U.S. Pat. Nos. 5,810,678, 08/706,008, filed Aug. 30,1996, now U.S. Pat. No. 5,813,923, and 08/603,057, filed Feb. 16, 1996,now U.S. Pat. No. 5,759,676, which are continuation-in-part applicationsof U.S. patent application Ser. No. 08/482,522, filed Jun. 7, 1995, nowU.S. Pat. No. 5,688,191, the entire disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to golf balls, and more specifically,to a multilayer golf ball. In particular, this invention relates to agolf ball having a core, a cover and at least one intermediate layerdisposed between the core and cover, wherein the intermediate layer isformed from a blend comprising thermoplastic or thermoset polyurethanes.The multilayer golf balls of the present invention have been found toprovide the distance and durability characteristics approaching that ofa conventional two piece ball while also providing the feel and “click”similar to that of a conventional wound golf ball.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general types or groups:two piece balls or three piece balls, the latter including wound balls.The difference in play characteristics resulting from these differenttypes of constructions can be quite significant.

Balls having a two piece construction are generally most popular withthe average recreational golfer because they provide a very durable ballwhile also providing maximum distance. Two piece balls are made with asingle solid core, usually formed of a crosslinked rubber, which isencased by a cover material. Typically the solid core is formed ofpolybutadiene which is chemically crosslinked with zinc diacrylateand/or similar crosslinking agents and is covered by a tough, cut-proofblended cover. The cover is generally formed of a material such asSURLYN®, which is a trademark for an ionomer resin produced by DuPont.The combination of the core and cover materials provide a “hard” ballthat is virtually indestructible by golfers. Further, such a combinationimparts a high initial velocity to the ball which results in improveddistance. Because the materials of which the ball is formed are veryrigid, two piece balls have a hard “feel” when struck with a club.Likewise, due to their hardness, these balls have a relatively low spinrate which provides greater distance.

At the present time, the wound ball remains the preferred ball of themore advanced players due to its spin and feel characteristics. Woundballs typically have either a solid rubber or liquid center core aroundwhich many yards of a stretched elastic thread or yam are wound. Thewound core is then covered with a durable cover material such as aSURLYN® or similar material or a softer cover such as balata orpolyurethane. Wound balls are generally softer and provide more spinthan non-would balls, which enables a skilled golfer to have morecontrol over the ball's flight and final position. Particularly, withapproach shots into the green, the high spin rate of soft, wound ballsenables the golfer to stop the ball very near its landing position.

Manufacturers place a great deal of emphasis on producing golf ballsthat consistently achieve the highest possible initial velocity withoutexceeding the United States Golf Association's (“USGA”) limit of 77.7m/s (255 ft/s) when struck with a driver with a clubhead speed of 39.6m/s (130 ft/s). In an effort to meet the demands of the marketplace,manufacturers strive to produce golf balls having initial velocities asclose as possible to the USGA initial velocity maximum, and yet maintainan acceptable feel and compression.

A number of patents have been issued which are directed towardsmodifying the properties of a conventional two piece ball by alteringthe typical single layer core and single cover layer construction toprovide a multi-layer ball having such as a dual cover layer, dual corelayer and/or a ball having a mantle layer disposed between the cover andthe core. The inventions disclosed in the prior art patents are directedtowards improving a variety such golf balls' physical properties and“in-play” characteristics.

Several patents are directed towards improving the carry distance ofsuch balls. For example, U.S. Pat. No. 4,863,167 relates to a threepiece solid golf ball having increased flight distance, wherein the ballhas a center portion and an outer layer formed from a rubbercomposition, wherein the outer layer is harder than the center portionand further contains a gravity filler so as to impart a higher specificgravity to the outer layer than that of the center portion. U.S. Pat.No. 5,184,828 relates to a solid three-piece golf ball having improvedrebound characteristics and carry distance while maintaining an adequatespin rate, wherein these characteristics are obtained by controlling thesize of the polybutadiene inner core and outer layer as well as theirspecific gravity and hardness. According to the '828 patent, the key toobtaining the desired rebound characteristics is that the maximumhardness (42-62 Shore D) must be located at the interface between thecore and the mantle and the hardness must then decrease both inwardlyand outwardly. U.S. Pat. No. 4,714,253 is also directed towards athree-piece golf ball having an excellent rebound coefficient. This golfball has a core with a Shore C hardness of 57-80 in its center, but notmore than 83 Shore C at a distance between 5-10 mm from its center andan outer layer with a Shore C hardness of 70-83.

Additionally, there are a number of patents directed towards improvingthe spin, click and feel of solid balls while maintaining the distanceprovided by the solid construction. For example, U.S. Pat. No. 5,072,944discloses a three-piece solid golf ball having a center layer and anouter layer which are prepared from a rubber composition, wherein it isdesirable that the center core layer is softer than the outer layer, thelayers having a hardness (Shore C) of 25-50 and 70-90, respectively.

U.S. Pat. No. 4,625,964 relates to a solid golf ball having apolybutadiene rubber core of a diameter not more than 32 mm, apolybutadiene rubber intermediate layer having a specific gravity oflower than that of the core material, and a cover. U.S. Pat. No.4,650,193 is directed towards a solid golf ball having a core comprisinga central portion and an integral outer layer, wherein the core is acurable elastomer such as polybutadiene which is treated with a curealtering agent to soften an outer layer of the core, to produce acentral layer with a hardness (Shore C) of greater than 75 and an outerlayer with a hardness (Shore A) of less than 80.

U.S. Pat. No. 4,848,770 discloses a non-wound three-piece golf ballwhich includes a core of a highly filled synthetic rubber or polymericmaterial, an intermediate mantle of an unfilled synthetic rubber and acover. The core and intermediate mantle have a hardness of between 50-95Shore D. U.S. Pat. No. 5,002,281 is directed towards a three-piece solidgolf ball which has an inner core having a hardness of 25-70 (Shore C),an outer shell having a hardness of 80-95 (Shore C) and a cover.Further, the specific gravity of the inner core must be greater than1.0, but less than or equal to that of the outer shell, which must beless than 1.3.

The prior art discloses a variety of materials other than polybutadienefor use as intermediate layers. For example, U.S. Pat. No. 5,253,871concerns a golf ball having a three piece structure comprising anelastomer core, an intermediate layer of a thermoplastic materialcontaining at least 10% of ether block copolymer, preferably blendedwith an ionomer, and a thermoplastic cover. U.S. Pat. No. 5,681,898 isdirected to a multilayer golf ball having a conventional polybutadienecore, an ionomer cover and an intermediate layer formed from a blend ofan ethylene methacrylic acid copolymer and a vulcanizate formed frompolybutadiene and a peroxide curing agent. U.S. Pat. Nos. 5,439,227 and5,556,098 both disclose multilayer golf balls which have a conventionalpolybutadiene core, conventional covers and an intermediate layer formedfrom a polyetherester block copolymer filled with zinc oxide andoptionally blended with an ionomer.

Further, there are also several patents which are directed to golf ballshaving multiple cover layers. For example U.S. Pat. No. 4,431,193relates to a golf ball having a multilayer cover wherein the inner layeris a hard, high flexural modulus ionomer resin and the outer layer is asoft, low flexural modulus ionomer resin, and wherein either or bothlayers may comprise a foamed ionomer resin. U.S. Pat. No. 5,314,187 alsorelates to golf balls having a multiple layer cover, wherein the outerlayer is molded over the inner layer and comprises a blend of balata andan elastomer and the inner layer is an ionomer resin. U.S. Pat. No.4,919,434 is directed towards a golf ball having a cover which comprisesan inner layer and an outer layer each of which comprise a thermoplasticresin, preferably the layers comprise of materials that are capable offusion bonding with each other.

However, none of the patents discussed above disclose a multilayer ballwhich employs the materials and has the improved physical properties asdisclosed herein.

SUMMARY OF THE INVENTION

The present invention is directed towards a golf ball comprising a core,a cover, and at least one intermediate layer disposed between the coreand the cover; and wherein the intermediate layer is formed from acomposition comprising at least one thermoplastic or thermosetpolyurethane material, wherein the golf ball has a compression of about75 to of less than about 85. In one embodiment, the golf ball has acompression of about 75 to about 85. about 85. In a preferredembodiment, the cover has a hardness of about 60 to about 72 Shore D.

In one embodiment, the intermediate layer has a hardness of betweenabout 35 and 60 Shore D. In another embodiment, the cover hardness andthe intermediate layer hardness have a first ratio from about 1.2 toabout 2.1. In still another embodiment, the core has a hardness suchthat a second ratio of the intermediate layer hardness to the corehardness is about 0.64 to about 0.91. In a preferred embodiment, thecore hardness is less than about 80 Shore C.

Preferably, the intermediate layer has a Shore D hardness of about 37 toabout 45 and a flexural modulus of at least about 10,000 psi. In oneembodiment, the composition is solely thermoplastic polyurethanematerial. In another embodiment, the intermediate layer compositionfurther comprises an ethylene methacrylic/acrylic acid copolymer.

In another embodiment, the intermediate layer further comprisesadditional thermoplastic material selected from the group consisting ofpolyesterester block copolymers, polyetherester block copolymers,polyetheramide block copolymers, ionomer resins, dynamically vulcanizedthermoplastic elastomers, styrene-butadiene elastomers with functionalgroups such as maleic anhydride or sulfonic acid attached, thermoplasticpolyesters, polymers formed using a metallocene catalyst, and mixturesthereof. Preferably, the thermoplastic or thermoset polyurethanematerial is present in an amount from about 25 to about 75 percent byweight.

In still another embodiment, the composition further comprises a secondthermoplastic or thermoset polyurethane. Preferably, the intermediatelayer has a thickness no greater than about 0.125 inches. In anotherembodiment, the intermediate layer has a specific gravity of at leastabout 1.14. In a preferred embodiment, the intermediate layer has aspecific gravity of greater than 1.2. In yet another embodiment, theblend further comprises a density-adjusting filler. Preferably, thefiller comprises barium sulfate, zinc oxide, titanium dioxide, andmixtures thereof. If a filler is present, it preferably comprises zincoxide present in an amount from about 5 to about 40 weight percent.

In another embodiment, the core has a specific gravity of about 1 toabout 1.2. Additionally, it is preferred that the core has a diameter ofno greater than about 1.51 inches. In still another embodiment, the corehas a Shore C hardness of less than about 80. Preferably, the corecomprises a blend of polybutadiene and calcium oxide, and the at leastone intermediate layer comprises the polyurethane material present in anamount of about to about 75 weight percent, a copolymer of ethylene andmethacrylic acid present in an amount from about 10 to about 50 weightpercent, and zinc oxide present in an amount from about 20 to about 30weight percent. Additionally, it is preferred that the cover comprises ablend of at least one ionomer.

The present invention is also directed to a golf ball comprising a core,a cover, and at least one intermediate layer disposed between the coreand the cover, wherein the core has a hardness of less than about 80Shore C; and the intermediate layer is formed from a blend comprising athermoplastic polyurethane material, wherein the golf ball has acompression of about 75 to about 85, and wherein the intermediate layerhas a hardness of between about 35 and about 50 Shore D. Preferably, thecover has a hardness of about 60 to about 72 Shore D.

In one embodiment, the core has a Bashore resilience of between about 30to about 80. Preferably, the core resilience is between about 40 andabout 70. In another embodiment, the intermediate layer has a Bashoreresilience of between about 35 and about 75. Preferably, theintermediate layer resilience is between about 60 and about 70.

The present invention is also directed to a golf ball comprising a solidcore, an intermediate layer, and a cover, wherein the solid core has adiameter of between about 1.25 and about 1.51 inches and a specificgravity of between about 1 and 1.2; wherein the intermediate layercomprises a polyurethane resin and has a hardness of between about 20and about 60 Shore D and a specific gravity of greater than about 1.2and greater than that of the solid core; and wherein the cover comprisesan ionomer resin and has a thickness greater than about 0.04 inches anda hardness of between about 60 and about 72 Shore D.

In one embodiment, the core diameter is between about 1.3 and about 1.48inches. In another embodiment, the intermediate layer has a specificgravity of between about 1.21 and about 1.3. Preferably, theintermediate layer has a specific gravity of between about 1.23 andabout 1.29. In another embodiment, the cover thickness is between about0.04 and about 0.41 inches. In still another embodiment, theintermediate layer has a thickness of between about 0.02 and about 0.125inches. In a preferred embodiment, the intermediate layer has a diameterof between about 1.27 and about 1.64 inches.

The present invention is also directed to a golf ball comprising a core,a cover of at least one layer, and at least one intermediate layerdisposed between the core and the cover; wherein the intermediate layeris formed from a composition comprising at least one thermoplastic orthermoset polyurethane material, and has a thickness of about 0.025 toabout 0.125 inches, an outer diameter of about 1.41 inches to about 1.68inches, and a Shore D hardness of less than about 60; and wherein thegolf ball has a compression of less than about 85, preferably from about75 to about 85. In one embodiment, the core diameter is from about 1.25inches to about 1.63 inches. In a preferred embodiment, the cover has aShore D hardness of about 68 to about 72. In another embodiment, theratio of the cover material hardness to the intermediate layer materialhardness is greater than about 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following terms that are used in this application are defined interms of the enumerated ASTM tests:

Specific gravity ASTM D-297¹ Flexural (Flex) Modulus ASTM D-790² Shore DHardness ASTM D-2240 Shore C Hardness ASTM D-2240 ¹Tests were carriedout in lab conditions where temperature was controlled to 20-23° C.Humidity was not controlled. ²Tests were carried out using a 0.5 in/mincross-head speed and a 2 inch span length in the three point bendingmode. Test samples were annealed at 23° C. and 50% Relative Humidity for40 hours.

As used herein, the terms “points” or “compression points” refer to thecompression scale or the compression scale based on the ATTI EngineeringCompression Tester. This scale, which is well known to those working inthis field, is used in determining the relative compression of a core orball. Some artisans use the Reihle compression scale instead of thestandard compression scale. Based on disclosure in U.S. Pat. No.5,368,304, column 20, lines 55-53 it appears that Reihle compressionvalues can be converted to compression values through the use of thefollowing equation:

 compression value=160−Reihle compression value.

As used herein, “COR” refers to Coefficient of Restitution, which isobtained by dividing a ball's rebound velocity by its initial (i.e.,incoming) velocity. This test is performed by firing the samples out ofan air cannon at a vertical steel plate over a range of test velocities(from 75 to 150 ft/s). A golf ball having a high COR dissipates asmaller fraction of its total energy when colliding with the plate andrebounding therefrom than does a ball with a lower COR. Unless otherwisenoted, the COR values reported herein are the values determined at anincoming velocity of 125 ft/s.

As used herein, the term “copolymer” refers to a polymer which is formedfrom two or more monomers.

As used herein, the term “pph” in connection with a batch formulationrefers parts by weight of the constituent per hundred parts of the basecomposition (e.g., elastomer).

The present invention is directed to an improved multilayer golf ballwhich comprises a core, a cover, and at least one intermediate layerdisposed between the core and the cover, wherein such golf ball providesa softer feel similar to a conventional wound ball, while also providingthe distance, durability and spin rates of a conventional two-pieceball. As discussed in detail below, the improved multilayer golf ball ofthe present invention is provided by forming a ball having variousstructural components (e.g. cover, core, intermediate layer) each havingdesired properties and which may be formed from a variety of materials.

The Core

Many conventional two-piece “distance” golf balls are formed with coreshaving a high compression (e.g., greater than about 90) in order toachieve the desired high finished ball COR and initial velocitynecessary to obtain long overall distance for the ball. Balls havingsuch high compression cores typically have a hard feel when struck witha golf club.

However, the golf balls of the present invention are formed with a corehaving a low compression, but still exhibit a finished ball COR andinitial velocity approaching that of conventional two-piece distanceballs. Preferably, the cores employed in the golf balls of the presentinvention have a compression of less than about 60, more preferablyabout 45 to about 60 and most preferably about 50 to 55. Likewise, it ispreferred that the finished balls made with such cores have a COR,measured at an inbound speed of 125 ft./s., of about 0.795 to about0.815, more preferably about 0.797 to about 0.812 and most preferablyabout 0.800 to about 0.810.

Additionally, it is preferred the core has a Shore C hardness of about65 to about 80, more preferably about 68 to about 75 and most preferablyabout 72 to about 75.

The cores employed in the golf balls of the present invention preferablyhave a diameter of about 1.25 inches to about 1.51 inches, morepreferably about 1.30 inches to about 1.48 inches and most preferablyabout 1.39 inches. The overall diameter of the core and the intermediatelayer is about 84 percent to about 97 percent of the overall diameter ofthe finished ball.

A representative base composition for forming the cores employed in thepresent invention comprises polybutadiene and, in parts by weight basedon 100 parts polybutadiene, 20-50 parts of a metal salt diacrylate,dimethacrylate, or monomethacrylate, preferably zinc diacrylate. Thepolybutadiene preferably has a cis-1,4 content of above about 90% andmore preferably above about 96%. Commercial sources of polybutadieneinclude Shell 1220 manufactured by Shell Chemical, NEOCIS® BR40manufactured by Enichem Elastomers, and UBEPOL® BR150 manufactured byUbe Industries, Ltd. If desired, the polybutadiene can also be mixedwith other elastomers known in the art, such as natural rubber, styrenebutadiene, and/or isoprene in order to further modify the properties ofthe core. When a mixture of elastomers is used, the amounts of otherconstituents in the core composition are usually based on 100 parts byweight of the total elastomer mixture.

Metal salt diacrylates, dimethacrylates, and monomethacrylates suitablefor use in the cores employed in this invention include those whereinthe metal is magnesium, calcium, zinc, aluminum, sodium, lithium ornickel. Zinc diacrylate is preferred, because it provides golf ballswith a high initial velocity in the United States Golf Association(“USGA”) test. The zinc diacrylate can be of various grades of purity.For the purposes of this invention, the lower the quantity of zincstearate present in the zinc diacrylate the higher the zinc diacrylatepurity. Zinc diacrylate containing less than about 10% zinc stearate ispreferable. More preferable is zinc diacrylate containing about 4-8%zinc stearate. Suitable, commercially available zinc diacrylates includethose from Rockland React-Rite and Sartomer. The preferredconcentrations of zinc diacrylate that can be used are 20-50 pph basedupon 100 pph of polybutadiene or alternately, polybutadiene with amixture of other elastomers that equal 100 pph.

Free radical initiators are used to promote cross-linking of the metalsalt diacrylate, dimethacrylate, or monomethacrylate and thepolybutadiene. Suitable free radical initiators for use in the inventioninclude, but are not limited to peroxide compounds, such as dicumylperoxide; 1,1-di(t-butylperoxy) 3,3,5-trimethyl cyclohexane; bis(t-butylperoxy) diisopropylbenzene; 2,5-dimethyl-2,5 di (t-butylperoxy)hexane; or di-t-butyl peroxide; and mixtures thereof. Other usefulinitiators would be readily apparent to one of ordinary skill in the artwithout any need for experimentation. The initiator(s) at 100% activityare preferably added in an amount ranging between about 0.05 and 2.5 pphbased upon 100 parts of butadiene, or butadiene mixed with one or moreother elastomers. More preferably, the amount of initiator added rangesbetween about 0.15 and 2 pph and most preferably between about 0.25 and1.5 pph.

Typical prior art golf ball cores incorporate 5 to 50 pph of zinc oxide(ZnO) in a zinc diacrylate-peroxide cure system that cross-linkspolybutadiene during the core molding process. However, in the presentinvention it is preferred that the ZnO in the core composition iseliminated in favor of calcium oxide (CaO). Cores produced from anadmixture containing CaO have been found to exhibit desirableperformance properties. In particular, when ZnO is replaced with CaO, ithas been observed that the initial velocity and COR of the core ismaintained, but the compression of the core is reduced by at least about4 compression points on the standard compression scale, and may bereduced as much as 6 points. Additionally, the combination of the use ofcalcium oxide and a higher percentage of zinc diacrylate can be used tomaintain the same compression as with the zinc oxide, but the initialvelocity and COR is significantly increased. Thus, by using calciumoxide, either the core compression can be lowered and the initialvelocity and COR maintained or the amount of zinc diacrylate can beincreased so that the core compression is the same and the initialvelocity and COR is increased.

Typically the calcium oxide added to the core-forming compositionemployed in the present invention is in the range of about 0.1 to 15,preferably 1 to 10, most preferably 1.25 to 5, parts calcium oxide perhundred parts of polybutadiene.

The core compositions employed in the present invention may also includefillers, added to the elastomeric composition to adjust the densityand/or specific gravity of the core. As used herein, the term “fillers”includes any compound or composition that can be used to vary thedensity and other properties of the subject golf ball core. Fillersuseful in the golf ball core according to the present invention include,for example, zinc oxide (in an amount significantly less than that whichwould be necessary without the addition of the calcium oxide), bariumsulfate, and regrind (which is recycled core molding matrix ground to 30mesh particle size). The amount and type of filler utilized is governedby the amount and weight of other ingredients in the composition, sincea maximum golf ball weight of 1.620 oz has been established by the USGA.Appropriate fillers generally used range in specific gravity from about2.0 to 5.6. In the preferred golf ball, the amount of filler in the coreis lower than that of a typical golf ball such that the specific gravityof the core is decreased.

The preferred range of specific gravities of the cores employed in thepresent invention is from about 1.0 to about 1.2, more preferably in therange of about 1.1 to about 1.18, depending upon the size of the core,cover, intermediate layer and finished ball, as well as the specificgravity of the cover and intermediate layer.

Other ingredients such as accelerators, e.g. tetra methylthiuram,processing aids, processing oils, plasticizers, dyes and pigments,antioxidants, as well as other additives well known to the skilledartisan may also be used in the present invention in amounts sufficientto achieve the purpose for which they are typically used.

The Intermediate Layer

The intermediate layer may comprise up to 100% by weight of adynamically vulcanized thermoplastic elastomer, a functionalizedstyrene-butadiene elastomer, a thermoplastic polyurethane, a metallocenepolymer or blends thereof. In a preferred embodiment of the presentinvention, the intermediate layer comprises a thermoplastic or thermosetpolyurethane.

In another preferred embodiment of the present invention, theintermediate layer is a blend of a first and a second component whereinthe first component is a dynamically vulcanized thermoplastic elastomer,a functionalized styrene-butadiene elastomer, a thermoplastic orthermoset polyurethane or a metallocene polymer and the second componentis a material such as a thermoplastic or thermoset polyurethane, athermoplastic polyetherester or polyetheramide, a thermoplastic ionomerresin, a thermoplastic polyester, another dynamically vulcanizedelastomer, another a functionalized styrene-butadiene elastomer, anothera metallocene polymer or blends thereof. In a more preferred embodiment,at least one of the first and second components comprises athermoplastic or thermoset polyurethane.

In another preferred embodiment, the intermediate layer of the golfballs of the present invention is formed from a blend which comprises anethylene methacrylic/acrylic acid copolymer. Below is a non-limitingexample of the chemical structure for suitable ethylenemethacrylic/acrylic acid copolymers:

wherein x=50 to 99%;

y=1 to 50%;

z=0 to 49%;

R₁=H or CH₃; R₂=CH₃ or isobomyl; and

n=0 to 12.

Specific acid-containing ethylene copolymers include ethylene/acrylicacid; ethylene/methacrylic acid; ethylene/acrylic acid/n- or isobutylacrylate; ethylene/methacrylic acid/n- or iso-butyl acrylate;ethylene/acrylic acid/methyl acrylate; ethylene/methacrylic acid/methylacrylate; ethylene/acrylic acid/iso-bomyl acrylate or methacrylate andethylene/methacrylic acid/isobomyl acrylate or methacrylate. Suitableethylene methacrylic/acrylic acid copolymers are sold commercially byDuPont under the tradename NUCREL®, with NUCREL® 960, NUCREL® RX9-1, and010 being preferred.

In another embodiment of the present invention, the intermediate layeris formed from a blend which comprises an ethylene methacrylic/acrylicacid copolymer and a second component which comprises a thermoplasticmaterial. Suitable thermoplastic materials for use in the intermediateblend include, but are not limited to, polyesterester block copolymers,polyetherester block copolymers, polyetheramide block copolymers,ionomer resins, dynamically vulcanized thermoplastic elastomers,styrene-butadiene elastomers with functional groups such as maleicanhydride or sulfonic acid attached, thermoplastic polyurethanes,thermoplastic polyesters, polymers formed using a metallocene catalyst(“metallocene polymers”) and/or blends thereof.

Suitable thermoplastic polyetheresters include materials which arecommercially available from DuPont under the tradename HYTREL® andinclude HYTREL® 3078, HYTREL® G3548W and HYTREL® G4078W. Suitablethermoplastic polyetheramides are commercially available fromElf-Atochem of Philadelphia, Pa, under the tradename PEBAX® and includePEBAX® 2533, PEBAX® 1205 and PEBAX® 4033. Suitable thermoplastic ionomerresins include any number of olefinic based ionomers such as SURLYN®,available from E. I. DuPont de Nemours and Co., of Wilmington, Del., andIOTEK®, available from Exxon Corporation of Houston, Tex. Suitabledynamically vulcanized thermoplastic elastomers include SANTOPRENE®,SARLINK®, VYRAM®, DYTRON® and VISTAFLEX®. SANTOPRENE® is the trademarkfor a dynamically vulcanized PP/EPDM. SANTOPRENE® 203-40 is an exampleof a preferred SANTOPRENE® and is commercially available from AdvancedElastomer Systems. Examples of suitable functionalized styrene-butadieneelastomers, i.e., styrene-butadiene elastomers with functional groupssuch as maleic anhydride or sulfonic acid, include KRATON FG-1901x andFG-1921x, which are available from the Shell Corporation of Houston,Tex. Examples of suitable thermoplastic polyurethanes include ESTANE®58133, ESTANE® 58134 and ESTANE® 58144, which are commercially availablefrom the B. F. Goodrich Company of Cleveland, Ohio. Suitable metallocenepolymers, i.e., polymers formed with a metallocene catalyst includethose commercially available from Sentinel Products of Hyannis, Mass.Suitable thermoplastic polyesters include polybutylene terephthalate.

Preferably, the second component of the intermediate layer blendcomprises polyetherester block copolymer, with HYTREL® 3078 being aparticularly preferred polyetherester block copolymer.

Many prior art intermediate layers generally have a specific gravity ofabout 1 or less. However, in a preferred embodiment, the intermediatelayer employed in the golf balls of the present invention has a specificgravity greater than 1.2, preferably about 1.21 to about 1.30, morepreferably about 1.23 to about 1.29 and most preferably about 1.27.

The desired specific gravity of the intermediate layer may be obtainedby adding a filler such as barium sulfate, zinc oxide, titanium dioxideand combinations thereof to the intermediate layer blend. Zinc oxide isthe preferred filler.

The intermediate layers of the present invention are formed from anintermediate layer blend comprising up to 100 percent by weight of anethylene methacrylic/acrylic acid copolymer. In a preferred embodimentof the present invention, the intermediate layer is formed from a blendof about 1 to about 99 percent by weight ethylene methacrylic/acrylicacid copolymer, about 0 to about 75 percent by weight of the secondthermoplastic component (as describe above) and about 0 to about 50percent by weight zinc oxide. In one embodiment of the presentinvention, the intermediate layer is formed from a blend of about 10 to50 percent by weight ethylene methacrylic/acrylic acid copolymer, 25 to75 percent by weight of a second thermoplastic component and about 5 toabout 40 percent by weight zinc oxide. In a most preferred embodiment ofthe present invention, the intermediate layer is formed from a blend ofabout 15 to about 25 percent by weight ethylene methacrylic/acrylic acidcopolymer, about 50 to about 60 percent by weight of a secondthermoplastic component and about 20 to about 30 percent by weight zincoxide. In another embodiment of the invention, the second thermoplasticcomponent is present in the intermediate layer blend in an amount ofless than 50 percent by weight, and preferably 30 to 45 percent byweight.

A specific example of a most preferred intermediate blend compositioncomprises about 20 percent by weight NUCREL® 960, about 57 percent byweight HYTREL® 3078 and about 23 percent by weight zinc oxide.

The intermediate layer blend preferably has a flexural modulus of lessthan about 10,000 psi, more preferably about 5,000 to about 8,000 psiand most preferably about 7,500 psi. Likewise, the intermediate layersemployed in the golf balls of the present invention preferably have aShore D hardness of about 35 to 50, more preferably about 37 to about 45and most preferably about 40. In another embodiment, the intermediatelayers preferably have a Shore D hardness of less than about 60, morepreferably about 20 to about 60, and most preferably about 30.

Preferably, the intermediate layer and core construction employed in thepresent invention have a compression of less than about 65, morepreferably about 50 to about 65 and most preferably about 50 to 55.

The intermediate layers employed in the golf balls of the presentinvention preferably have a thickness from about 0.020 inches to about0.125 inches, more preferably about 0.035 inches to about 0.085 inchesand most preferably about 0.06 inches.

In another embodiment, the thickness of the intermediate layer is about0.025 inches to 0.125 inches, more preferably about 0.040 inches to 0.10inches, and most preferably about 0.06 inches. The outer diameter of theintermediate layer is preferably about 1.510 inches.

The Cover Layer

The cover layer of the present invention comprises at least one layer ofa thermoplastic or thermosetting material. Any number of a wide varietyof cover materials may be used in the present invention such as ionomerresins, polyurethanes, balata and blends thereof, with ionomer resinsbeing preferred.

Ionomers, such as acid-containing ethylene copolymer ionomers, includeE/X/Y copolymers where E is ethylene, X is a softening comonomer such asacrylate or methacrylate present in 0-50 (preferably 0-25, mostpreferably 0-2), weight percent of the polymer, and Y is acrylic ormethacrylic acid present in 5-35 (preferably 10-35, most preferably15-20) weight percent of the polymer, wherein the acid moiety isneutralized 1-90% (preferably at least 40%, most preferably at leastabout 60%) to form an ionomer by a cation such as lithium, sodium,potassium, magnesium, calcium, barium, lead, tin, zinc or aluminum, or acombination of such cations, lithium, sodium and zinc being the mostpreferred. Specific acid-containing ethylene copolymers includeethylene/acrylic acid, ethylene/methacrylic acid, ethylene/acrylicacid/n-butyl acrylate, ethylene/methacrylic acid/n-butyl acrylate,ethylene/methacrylic acid/iso-butyl acrylate, ethylene/acrylicacid/iso-butyl acrylate, ethylene/methacrylic acid/n-butyl methacrylate,ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic acid/methylacrylate, ethylene/methacrylic acid/methyl acrylate,ethylene/methacrylic acid/methyl methacrylate, and ethylene/acrylicacid/n-butyl methacrylate. Preferred acid-containing ethylene copolymersinclude ethylene/methacrylic acid, ethylene/acrylic acid,ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylicacid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate andethylene/acrylic acid/methyl acrylate copolymers. The most preferredacid-containing ethylene copolymers are ethylene/methacrylic acid,ethylene/acrylic acid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

The manner in which these ionomers are made is well known in the art asdescribed in e.g. U.S. Pat. No. 3,262,272. As mentioned above, ionomerresins are commercially available from E. I. DuPont de Nemours and Co.of Wilmington, Del., under the tradename SURLYN®, and from ExxonCorporation of Houston, Tex., under the tradename IOTEK®.

As is well known in the art, ionomer resins may be blended in order toobtain a cover having desired characteristics. For this reason, it ispreferable that the covers of the golf balls of the present invention beformed from a blend of two or more ionomer resins. A particularlypreferred cover material for use in the present invention is formed froma blend of about 50 percent by weight SURLYN® 7940, about 47 percent byweight SURLYN® 8940 and about 3 percent by weight SURLYN® 8660.

The cover layers employed in the present invention preferably have aShore D hardness of about 60 to about 72, more preferably about 65 toabout 70 and most preferably about 68 to about 70.

The multi-layer golf ball of the invention can have an overall diameterof any size. Although the United States Golf Association specificationslimit the minimum size of a competition golf ball to 1.680 inches indiameter or more, there is no specification as to the maximum diameter.Moreover, golf balls of any size can be used for recreational play. Thepreferred diameter of the present golf balls is from about 1.680 inchesto about 1.800 inches. The more preferred diameter is from about 1.680inches to about 1.760 inches. The most preferred diameter is about 1.680inches to about 1.740 inches.

The golf balls of the present invention have an overall maximumcompression of about 85, preferably about 75 to about 85, morepreferably about 80 to about 85 and most preferably about 82.

The golf balls of the present invention can be made by any conventionalprocesses employed in the golf ball art. For example, the solid corescan be either injection or compression molded. The mantle layer issubsequently injection or compression molded about the core. It isimportant that the mantle material be able to sustain the temperaturesapplied during the application of the cover layer. The cover layer orlayers are then injection or compression molded or cast about the mantlelayer.

EXAMPLES Example 1

Table I below provides batch compositions for intermediate layer blendsfor forming the novel multilayer golf balls of the present invention.However, it is to be understood that the examples are only forillustrative purposes and in no manner is the present invention limitedto the specific disclosures therein.

In particular, batch numbers 2-4 provide intermediate layer blendscomprising NUCREL® 960, HYTREL® 3078, and ZnO used to form theintermediate layers of the golf balls of the present invention. Batchnumber 1 provides a control intermediate layer blend.

TABLE I Intermediate Layer Formulations % % Flexural Batch NUCREL ®HYTREL ® % Modulus Specific # 960 3078 ZnO (psi) Gravity 1 — 80 20 42101.27 2 10 75 15 5560 1.21 3 20 70 10 7710 1.17 4 30 65  5 7250 1.14

Example 2

Multilayer golf balls were made having intermediate layers formed fromthe batch compositions set forth in Table I. Several dozen golf ballswere formed using each batch composition and subsequently tested forcompression, spin rate and initial velocity.

The cores of all of the multilayer balls were formed by compressionmolding a blend of the batch formulation set forth in Table II below.All of the cores had a diameter of 1.39 inches and were measured to havecompressions ranging from about 45 to about 55 and specific gravities offrom about 1.134 to about 1.146.

The intermediate layer blends of Table 1 were subsequently injectionmolded about the cores to form the intermediate layers of the ballshaving an outer diameter of about 1.51 inches.

TABLE II Core Formulation Parts Material Per Hundred Polybutadiene(Shell 1220) 76.0 Rubber (Enichem Br40) 24.0 Pigment 0.10 ZincDiacrylate 24.79 Calcium Oxide 2.16 Regrind 6.47 Peroxide (VAROX ®) 0.43Peroxide (EF-60) (DBDB) 0.16 Filler 22.64 Process Oil 1.50

All of the multilayer balls had a cover composition formed by injectionmolding a blend comprising 50% SURLYN® 7940 and 50% SURLYN® 8140 aboutthe intermediate layers and were subsequently finished usingconventional clear coating and buffing techniques. The finished golfballs had an outer diameter of about 1.68 inches. These balls weretested for initial velocity, compression, cover hardness and COR, theresults of such tests are set forth in Table III below.

The balls were also tested for spin rate using a True Temper TestMachine configured to strike the balls with a driver and an 8-Iron. Alsotested for comparison purposes were conventional two piece “distance”balls (Titleist® HP2 Distance and Pinnacle® Gold). The test data for allof these balls is set forth in Tables III-V below.

TABLE III Com- Cover³ COR³ Velocity¹ pression¹ Weight¹ Hardness (at Ball(ft/s) (Ball) (oz) (Shore D) 125 ft/s) Pinnacle ® Gold⁴ 252.5 95 1.60568 0.809 Titleist ® HP2 253.0 99 1.600 71 0.810 Distance⁴ Ball 1 251.981 1.610 71 0.814 Ball 2 252.3 84 1.584 72 0.814 Ball 3 252.2 84 1.58871 0.813 Ball 4 251.9 84 1.590 69 0.810 ¹Average based on results for 12balls ²Average based on results for 3 balls ³Average based on resultsfor 6 balls ⁴Historical data for commercial balls

TABLE IV Spin Rates For Driver Launch Spin Club Speed Ball Type Angle(°) (rpm) (ft/s) Pinnacle ® Gold 9.1 ± 0.3 3032 ± 135 158.6 ± 0.6Titleist ® HP2 Distance 9.0 ± 0.3 2977 ± 60  158.6 ± 1.0 Ball 1 9.1 ±0.5 2973 ± 195 158.4 ± 0.6 Ball 2 9.1 ± 0.5 3001 ± 66  158.9 ± 0.7 Ball3 9.1 ± 0.4 3006 ± 121 158.9 ± 0.8 Ball 4 9.0 ± 0.3 3007 ± 140 159.0 ±0.6

TABLE V Spin Rate For 8-Iron Launch Spin Club Speed Ball Type Angle (°)(rpm) (ft/s) Pinnacle ® Gold 19.2 ± 0.4 8160 ± 218 116.4 ± 0.1Titleist ® HP2 Distance 19.4 ± 0.5 8375 ± 171 116.3 ± 1.3 Ball 1 19.2 ±0.5 7970 ± 246 116.2 ± 0.7 Ball 3 19.3 ± 0.2 7972 ± 168 116.5 ± 0.9 Ball4 19.4 ± 0.3 7940 ± 171 117.0 ± 1.3

As shown by results reported in Tables III-V, golf balls having anintermediate layer comprising NUCREL® 960, HYTREL® 3078, and ZnO have ahigh initial velocity and low spin rate. Moreover, the balls of thepresent invention have initial velocities approaching those ofconventional two-piece “distance” balls, but have a considerably lowercompression, which provides a much softer feel, more like a wound ball.Still further, these balls are easy to manufacture compared to theconventional wound ball. Thus, these balls provide the advantages of twopiece “distance” balls with low spin rates and high velocity, but alsoprovide a softer feel than such balls.

Example 3

Multilayer golf balls were made having intermediate layers formed from ablend comprising 20% NUCREL® 960, 57% HYTREL® 3078, and 23% ZnO. Thisintermediate layer blend was injection molded about cores formed fromthe batch formulation set forth in Table II. A cover was formed byinjection molding a blend of 50% SURLYN® 7940, 47% SURLYN® 8940, and 3%SURLYN® 8660 around the intermediate layer and subsequently finishingthe balls using conventional clear coating and buffing techniques.

The balls were tested for initial velocity, compression, cover hardnessand COR, as well as for spin rate when struck by a driver and an 8-Ironusing a True Temper Test Machine. The results of such tests are setforth below in Tables VI and VII below.

TABLE VI Com- Cover Velocity¹ pression¹ Weight¹ Hardness² COR³ Specific(ft/s) (Ball) (oz) (Shore D) (at 125 ft/s) Gravity 251.5 82 1.607 690.801 1.27 ¹Average based on results for 12 balls ²Average based onresults for 3 balls ³Average based on results for 6 balls

TABLE VII Launch Club Angle (°) Spin (rpm) Club Speed (ft/s) Driver  9.2± 0.5 3015 ± 221 160.3 ± 0.7 8 Iron 19.3 ± 0.6 7807 ± 252 115.6 ± 0.8

TABLE VIII Mantle Layer Compositions and Properties % Strain HardnessResilience Flex Modulus Tensile Modulus at Sample (Shore D) (%) (psi)(psi) Break 1A 0% Estane 58091 28 54  1,720   756 563 100% Estane 588611B 25% Estane 58091 34 41  2,610  2,438 626 75% Estane 58861 1C 50%Estane 58091 44 31 10,360 10,824 339 50% Estane 58861 1D 75% Estane58091 61 34 43,030 69,918 149 25% Estane 58861 1E 100% Estane 58091 7846 147,240  211,288   10 0% Estane 58861 2A 0% Hytrel 5556 40 47  8,500 7,071 527 100% Hytrel 4078 2B 25% Hytrel 5556 43 51 10,020  9,726 44175% Hytrel 4078 2C 50% Hytrel 5556 45 47 12,280 10,741 399 50% Hytrel4078 2D 75% Hytrel 5556 48 53 13,680 13,164 374 25% Hytrel 4078 2E 100%Hytrel 5556 48 52 12,110 15,231 347 0% Hytrel 4078 3A 0% Hytrel 5556 3062  3,240  2,078 810 100% Hytrel 3078 no break 3B 25% Hytrel 5556 37 59 8,170  5,122 685 75% Hytrel 3078 3C 50% Hytrel 5556 44 55 15,320 10,879590 50% Hytrel 3078 3D 75% Hytrel 5556 53 50 19,870 16,612 580 25%Hytrel 3078 3E 100% Hytrel 5556 58 50 24,840 17,531 575 0% Hytrel 30784A 0% Hytrel 4078 46 51 11,150  8,061 597 100% Pebax 4033 4B 25% Hytrel4078 46 53 10,630  7,769 644 75% Pebax 4033 4C 50% Hytrel 4078 45 52 9,780  8,117 564 50% Pebax 4033 4D 75% Hytrel 4078 42 53  9,310  7,996660 25% Pebax 4033 4E 100% Hytrel 4078 40 51  9,250  6,383 531 0% Pebax4033 5A 0% Hytrel 3078 77 50 156,070  182,869   9 100% Estane 58091 5B25% Hytrel 3078 65 48 87,680 96,543  33 75% Estane 58091 5C 50% Hytrel3078 52 49 53,940 48,941 102 50% Estane 58091 5D 75% Hytrel 3078 35 5412,040  6,071 852 25% Estane 58091 5E 100% Hytrel 3078 29 50  3,240 2,078 810 0% Estane 58091 no break 6A 100% Kraton 1921 29 59 24,30029,331 515 0% Estane 58091 0% Surlyn 7940 6B 50% Kraton 1921 57 4956,580 — 145 50% Estane 58091 0% Surlyn 7940 6C 50% Kraton 1921 56 5528,290 28,760 295 0% Estane 58091 50% Surlyn 7940 7A 33.3% Pebax 4033 4850 41,240 30,032 294 33.3% Estane 58091 33.3% Hytrel 3078 7B 30% Pebax4033 48 50 30,650 14,220 566 40% Estane 58091 10% Hytrel 3078 7C 20%Pebax 4033 41 54 24,020 16,630 512 40% Estane 58091 40% Hytrel 3078

The term “about,” as used herein in connection with one or more numbersor numerical ranges, should be understood to refer to all such numbers,including all numbers in a range.

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended solely as illustrations of several aspects of theinvention. Any equivalent embodiments are intended to be within thescope of this invention. Indeed, various modifications of the inventionin addition to those shown and described herein will become apparent tothose skilled in the art from the foregoing description. Suchmodifications are also intended to fall within the scope of the appendedclaims.

What is claimed is:
 1. A golf ball comprising: a core, a cover, and atleast one intermediate layer disposed between the core and the cover,wherein the intermediate layer is formed from a composition comprisingat least one thermoplastic or thermoset polyurethane material, whereinthe intermediate layer has a specific gravity of at least about 1.14,and wherein the golf ball has a compression of about 85 or less.
 2. Thegolf ball of claim 1, wherein the cover has a hardness of about 60 toabout 72 Shore D.
 3. The golf ball of claim 1, wherein the intermediatelayer has a hardness of about 35 to about 60 Shore D.
 4. The golf ballof claim 3, wherein the cover hardness and the intermediate layerhardness have a first ratio from about 1.2 to about 2.1.
 5. The golfball of claim 3, wherein the core has a hardness such that a secondratio of the intermediate layer hardness to the core hardness is about0.64 to about 0.91.
 6. The golf ball of claim 5, wherein the corehardness is less than about 80 Shore C.
 7. The golf ball of claim 1,wherein the intermediate layer has a Shore D hardness of about 37 toabout 45 and a flexural modulus of at least about 10,000 psi.
 8. Thegolf ball of claim 1, wherein the composition comprises thermoplasticpolyurethane material.
 9. The golf ball of claim 1, wherein theintermediate layer composition further comprises an ethylenemethacrylic/acrylic acid copolymer.
 10. The golf ball of claim 1,wherein the intermediate layer further comprises additionalthermoplastic material selected from the group consisting ofpolyesterester block copolymers, polyetherester block copolymers,polyetheramide block copolymers, ionomer resins, dynamically vulcanizedthermoplastic elastomers, styrene-butadiene elastomers with functionalgroups comprising maleic anhydride or sulfonic acid, thermoplasticpolyesters, polymers formed using a metallocene catalyst, and mixturesthereof.
 11. The golf ball of claim 1, wherein the thermoplastic orthermoset polyurethane material is present in an amount from about 25 toabout 75 percent by weight.
 12. The golf ball of claim 1, wherein thecomposition further comprises a second thermoplastic or thermosetpolyurethane.
 13. The golf ball of claim 1, wherein the intermediatelayer has a thickness no greater than about 0.125 inches.
 14. The golfball of claim 1, wherein the intermediate layer has a hardness of about78 Shore D or less.
 15. The golf ball of claim 1, wherein theintermediate layer has a specific gravity of greater than 1.2.
 16. Thegolf ball of claim 1, wherein the composition further comprises adensity-adjusting filler.
 17. The golf ball of claim 16, wherein thefiller comprises barium sulfate, zinc oxide, titanium dioxide, andmixtures thereof.
 18. The golf ball of claim 17, wherein the fillercomprises zinc oxide present in an amount from about 5 to about 40weight percent.
 19. The golf ball of claim 1, wherein the core has aspecific gravity of about 1 to about 1.2.
 20. The golf ball of claim 1,wherein the core has a diameter of no greater than about 1.51 inches.21. The golf ball of claim 1, wherein the core has a Shore C hardness ofless than about
 80. 22. The golf ball of claim 1, wherein the corecomprises a blend of polybutadiene and calcium oxide, and the at leastone intermediate layer comprises the polyurethane material present in anamount of about 25 to about 75 weight percent, a copolymer of ethyleneand methacrylic acid present in an amount from about 10 to about 50weight percent, and zinc oxide present in an amount from about 20 toabout 30 weight percent.
 23. The golf ball of claim 1, wherein the covercomprises a blend of at least one ionomer.
 24. A golf ball comprising: acore, a cover, and at least one intermediate layer disposed between thecore and the cover, wherein the core has a hardness of less than about80 Shore C; and the intermediate layer is formed from a blend comprisinga thermoplastic polyurethane material, wherein the golf ball has acompression of about 75 to about 85, and wherein the intermediate layerhas a hardness of between about 35 and about 50 Shore D.
 25. The golfball of claim 24, wherein the cover has a hardness of about 60 to about72 Shore D.
 26. The golf ball of claim 24, wherein the core has aBashore resilience of about 30 to about
 80. 27. The golf ball of claim26, wherein the core resilience is about 40 to about
 70. 28. The golfball of claim 24, wherein the intermediate layer has a Bashoreresilience of about 35 to about
 75. 29. The golf ball of claim 28,wherein the intermediate layer resilience is about 60 to about
 70. 30. Agolf ball comprising a solid core, an intermediate layer, and a cover,wherein the solid core has a diameter of about 1.25 to about 1.51 inchesand a specific gravity of about 1 to about 1.2; wherein the intermediatelayer comprises a polyurethane resin and has a hardness of about 20 toabout 60 Shore D and a specific gravity of greater than about 1.2 andgreater than that of the solid core; and wherein the cover comprises anionomer resin and has a thickness greater than about 0.04 inches and ahardness of about 60 to about 72 Shore D.
 31. The golf ball of claim 30,wherein the core diameter is about 1.3 to about 1.48 inches.
 32. Thegolf ball of claim 30, wherein the intermediate layer has a specificgravity of about 1.21 to about 1.3.
 33. The golf ball of claim 32,wherein the intermediate layer has a specific gravity of about 1.23 toabout 1.29.
 34. The golf ball of claim 30, wherein the cover thicknessis about 0.04 to about 0.41 inches.
 35. The golf ball of claim 30,wherein the intermediate layer has a thickness of about 0.02 to about0.125 inches.
 36. The golf ball of claim 30, wherein the intermediatelayer has a diameter of about 1.27 to about 1.64 inches.
 37. A golf ballcomprising: a core; a cover comprising at least one layer; at least oneintermediate layer disposed between the core and the cover and beingformed of a composition comprising at least one thermoset polyurethanematerial, wherein the intermediate layer has a Shore D hardness of lessthan about
 60. 38. The golf ball of claim 37, wherein the core has anouter diameter of about 1.25 inches to about 1.63 inches.
 39. The golfball of claim 37, wherein the ratio of the cover material hardness tothe intermediate layer material hardness is greater than about
 1. 40.The golf ball of claim 37, wherein the cover material hardness is about68 to 72 Shore D.
 41. The golf ball of claim 37, wherein the golf ballcompression is from about 75 to about
 85. 42. The golf ball of claim 1,wherein the golf ball compression is from about 75 to about
 85. 43. Thegolf ball of claim 1, wherein the cover is formed from a compositioncomprising thermoset or thermoplastic material.
 44. The golf ball ofclaim 43, wherein the cover has a hardness of about 60 to about 70 ShoreD.
 45. The golf ball of claim 43, wherein the cover is formed of atleast one ionomer, and wherein the at least one ionomer is a copolymerof ethylene and methacrylic acid.
 46. The golf ball of claim 43, whereinthe first composition further comprises a density-adjusting filler. 47.The golf ball of claim 46, wherein the first composition furthercomprises a copolymer of ethylene and methacrylic acid present in anamount from about 10 to about 50 weight percent, wherein thepolyurethane material present in an amount from about 25 to about 75weight percent, and wherein the density-adjusting filler is present inan amount from about 20 to about 30 weight percent.
 48. The golf ball ofclaim 43, wherein the core comprises a blend of polybutadiene andcalcium oxide.
 49. The golf ball of claim 43, wherein the core has ahardness of less than about 80 Shore C.